Articles which require high resistance against corrosion



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BENNO STRAUSS, BREDENEY, GERMANY, ASSIGNOR, BY MESNE ASSIGNMENTS, TO THE CHEMICAL FOUNDATION, INC., A CORPORATION OF DELAWARE.

ARTICLES WHICH REQUIRE HIGH RESISTANCE AGAINST CORROSION.

Specification of Letters Patent.

Patented Sept. 23, 1919.

No Drawing. Original application filed June 25, 1913, Serial No. 775,765. Divided and this application filed June 19, 1914, Serial No. 846,168. Renewed February 1, 1919. Serial No. 274,582.

To all whom it may concern: v

Be it known that I, Professor Doctor BENNO STRAUSS, a citizen of the German Empire, residing at Bredeney, Germany, have have invented certain new and useful Improvements in Articles Which Require High Resistance Against Corrosion, of which the following is a specification.

This application is 2 division of my application filed June 2., 1913, Serial No. 775,765.

This invention relates to articles such as gun barrels, turbine buckets and the like, which require a high resistance against corrosion, and it consists in the use of steel alloys for producing such articles, which contain from 6% to 25% chromium and from 20% to nickel and not over 1% carbon.

In the production of such articles it has up to now been recommended to use nickel steel containing about 10% nickel or from 25% to 30% nickel.

; It has now been proved by experiments that alloys of the above named composition possess considerably higher power of resistance to corrosion than the previously used nickel steel alloys.

The great power of resistance of these alloys will be evident from the following.

A bar from analloy of 20% chromium' and 2% nickel shows entirely shiny surfaces after it has been exposed for months to the influence of damp air, while bars of ordinary steel and bars of nickel steel containing 10% nickel show considerably corroded surfaces when exposed to damp air for the same length of time, and even nickel zteel with 25%. nickel show corroded suraces.

Taking the loss in weight of mild steel as 100, a corroding test in sea water gave the following losses in weight for:

Nickel steel with 10% nickel so Nickel steel with 25% nickel 44 Steel with 10% chromium and 3% nickeL 16 Steel with 20% chromium and 2% nickeL 9 At the same time the described alloy nickel-chrom-steel possesses better qualities two groups namely, alloys'which possess a hardness over 380 (in acordance with Brinell) in the forged state; and such alloys which possess .a hardness below 350 (also in accordance with Brinell) in the forged state.

To the first group belong alloys containing 6% chromium and 12% to 4% nickel or 12% chromium and 7% to 1}% nickel or 18% chromium and 1 to nickel.

Alloys of the first group which are difficult or almost impossible to work in the forged state can be made soft and easy to work if they are heated to a temperature between 500 C. and the critical point, and thereupon cooled quickly or slowly. The critical point is situated in accordance with the composition of the alloy, between 720 C. and 780 C.

If this heating treatment be preceded by a heating up to 800 C. to 1000 C. with a subsequent quick or slow cooling, the alloys will obtain in addition a great strength and toughness. By small additions of tungsten or vanadium the quality of strength of the alloys may be still more improved.

By means of a subsequent heating to from 800 C. to 900 C. and subsequent quick or slow cooling, the alloys will again become hard and be diflicult or impossible to work. This heating treatment forms con sequently a means for hardening after working of articles produced from these alloys. These alloys may therefore be employed for the production of ball bearings as Well as for the production of the balls therefor, or generally speaking, to articles; which are exposed to rust or to the action of sea water.

The alloys belonging to the second group may contain, for instance, the following proportions of chromium and nickel:

come unmagnetic.

I claim: I 1. Articles which require a high resist ance against corrosion said articles being nickel and not over 1% carbon, the pronmde from a steel alloy containing 6% to portion of chromium increasing as the pro- 25% chromium, 20% to 5% nickel and not portion of nickel decreases and vice versa.

over 1% carbon, the proportion of chro- In testimony whereof the foregoing spec- 5 niium increasing as the proportion of nickel ification is signed in the presence of two 15 decreases and vice versa. Witnesses.

2; Articles with a high resistance against BLNNO STRAUSS. [L.S.] corrosion which require to be unmagnetic, W itnesses: said articles being made from a, steel alloy ALBERT Norm,

10 containing 8% to 25% chromium, 20% to FRANCES Norm. 

